Introduction/Purpose Endovascular therapy is a widely accepted treatment modality for intracranial aneurysms due to its safety and efficacy. However, the treatment of very small intracranial aneurysms (≤3 mm) is still challenging, and the risk-benefit ratio of endovascular therapy for such aneurysms, especially those ruptured, remains unclear. This study aimed to systematically review the literature and conduct a meta-analysis to evaluate the safety and efficacy of endovascular treatment for ruptured very small intracranial aneurysms.

Materials and Methods We conducted this study following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered it with PROSPERO (CRD42023403959). We conducted a comprehensive search of PubMed and Scopus databases up to February 18, 2023, for original articles on endovascular treatment of ruptured intracranial aneurysms ≤ 3 mm. Only studies with a sample size of more than 10 were included. Statistical analysis was performed using R version 4.2.3, and a random-effect model was applied when I2 > 50% to account for heterogeneity. Pooled prevalence rates were calculated for occlusion rates, complications, and favorable long-term outcomes. odds ratios were calculated to compare outcomes between simple coiling and stent-assisted coiling (SAC).

Results Of the 600 studies screened, 23 studies with a total of 1335 endovascularly treated ruptured very small intracranial aneurysms were included in the final analysis. The mean age of the patients was 50.69, 482 (32.9%) patients were female, the mean Hunt-Hess Scale was 1.42, and 129 (8.8%) aneurysms originated from the posterior circulation. The overall success rate was 98%. The initial complete aneurysm occlusion rate (Raymond Roy Grade I) was 68% (95% confidence interval [CI]: 56.0 - 77.0), while the follow-up complete occlusion rate was 83% (95% CI: 72.0 - 90.0). Procedure-related complications included a 4% (95% CI: 3.0 - 5.0) aneurysm re-rupture rate, 4% (95% CI: 3.0 - 6.0) thromboembolism rate, 3% (95% CI: 1.0 - 7.0) coil herniation rate, and 3% (95% CI: 2.0 - 4.0) mortality rate. The recanalization rate was 7% (95% CI: 4.0 - 11.0), and the retreatment rate was 4% (95% CI: 3.0 - 6.0). The favorable long-term follow-up outcome (mRS 0-2) was observed in 90% (95% CI: 3.0 - 6.0) of cases. Comparison of outcomes between treatment by simple coiling and SAC revealed no significant difference between the two groups, except for a higher odd of recanalization in the coiling group (OR= 4.51; 95% CI: 1.31-9.54).

Conclusion Our meta-analysis demonstrates that endovascular treatment of ruptured very small intracranial aneurysms with a diameter ≤3 mm is a feasible, effective, and safe approach that is associated with favorable clinical outcomes in both the short and long term. However, more studies are needed to compare endovascular therapy with the clipping of such aneurysms.

Disclosures S. Samir Elawady: None. M. Mahdi Sowlat: None. S. Al Kasab: None. A. M Spiotta: None.